There is a continuing need, particularly in the coatings industry, to provide compositions which have low curing temperatures and, preferably, which cure at ambient temperature. There is also a continuing need to provide compositions which contain ever lower concentrations of volatile organic components. Additionally, it would be desirable to provide compositions which do not depend on organic isocyanates for curing.
However, previous approaches to meet these challenges generally have involved disadvantageous compromises among desirable coating composition properties such as molecular weight of the principal film forming resin, application viscosity of the composition, low curing temperature, and desirable properties of the cured film such as water resistance, flexibility, hardness, solvent resistance, etc.
One approach to address some of these challenges has been to employ curable compositions based on silyl-group-containing vinyl resins which have a main chain consisting essentially of vinyl polymer and having at least one silicon atom connected to a hydrolyzable group on a terminal or side chain. Such silyl-group-containing vinyl resins are described, for example, in U.S. Pat. No. 4,339,261. Two methods are disclosed for preparing the silyl-group-containing vinyl resins of the patent.
The first involves the reaction of a hydrosilane with a vinyl resin having carbon-carbon double bonds in the presence of a complex of a Group VIII transition metal. The preparation of such silyl group containing resins by this first method is also described in U.S. Pat. No. 4,191,713. The second method described in U.S. Pat. No. 4,399,261 for preparing the silyl group containing vinyl resin involves free radical copolymerization of a vinyl compound with a silane compound of specified formula having a polymerizable double bond therein, an example of the silane compound being gamma-methacryloxypropyltrimethoxysilane.
However, coating compositions based, for example, on such prior art resins exhibit a number of disadvantages. For example coating compositions based on such resins tend to cure to films which are ultimately too brittle or too inflexible for high performance coatings uses such as, for example, in automotive applications. Moreover, compositions based on such resins often do not cure as well as is desirable for a number of purposes, and typically contain lower total solids contents than is desirable for a number of purposes.
Objects of the present invention are to help meet these challenges based on a new class of compositions which is a subject of the present disclosure. Other objects of the invention will become apparent to the reader infra.